Ways to provide feedback to user during a running process

What are you trying to do?
I have a bokeh server app that does some moderately time consuming background work upon request by a user. I’m looking for ways to add a progress bar, or text-based feedback - like a log - as a widget in the app.

What have you tried that did NOT work as expected? If you have also posted this question elsewhere (e.g. StackOverflow), please include a link to that post.
I have tried to use a TextAreaInput widget to display messages generated by my backend processes. At the end of the process, plots are changed in the app so the user can tell it’s done. To send a message through the TextAreaInput widget, I set the .value property. The problem is that my messages don’t show up until the background work is finished. The widget does not display it’s new value until all the work is done, at which point I don’t really need it anymore.

If this is a question about Bokeh code, please include a complete Minimal, Reproducible Example so that reviewers can test and see what you see.
I can try to cobble together an example if someone thinks they can help.

In some cases, a screenshot of your plot will also be helpful.
n/a

@domesmack Bokeh currently only synchronizes things at the end of callback functions, so if you need to update UI and the “do some work” you will have to split the callback up. Unfortunately I am pressed for time just now and cannot provide a complete example, but the relevant API that you want to search for is add_next_tick_callback.